The new study, published in the journal Lancet, analyzed existing data from the well-known and controversial 2008 JUPITER trial (for Justification for the Use of Statins in Primary Prevention), which tested a single statin, Crestor (rosuvastatin), for the prevention of heart disease in healthy people with no history of heart problems.

It’s well-established that taking statins reduces cardiovascular risks in people who already have heart disease. But the JUPITER trial found that healthy people with no heart disease or high cholesterol — but with high levels of C-reactive protein (CRP), a marker for inflammation — also had significantly lower risks of nonfatal heart attacks and stroke when taking Crestor, compared with people not taking the drug. Those findings prompted the FDA to expand the eligible patient population for Crestor by millions.

The JUPITER trial, which included more than 17,000 participants, also suggested, however, that taking statins could raise diabetes risk in users — a finding that has been borne out by subsequent research. So Dr. Paul Ridker, the principal investigator of the original trial, and his colleagues at Brigham and Women’s Hospital in Boston took another look at the data.

They found that the increased diabetes risk applied almost exclusively to those people who already had risk factors for the disease, such as obesity or higher fasting blood-sugar levels. Over five years of follow-up, people who took Crestor but had no diabetes risk factors, did not see an increase in risk of the disease.

Among people with at least one major risk factor for diabetes, those taking Crestor were 28% more likely to develop diabetes than those taking placebo. But they were also 39% less likely to develop heart disease and 17% less likely to die, suggesting that even in high-risk people, the benefits of statins outweigh their diabetes risks. Among participants at low risk for diabetes, statin use reduced heart risk by 52% with no increased risk of diabetes.

Overall, among people at high risk of diabetes, the study estimated that 134 heart attacks, strokes or deaths were prevented, while 54 new cases of diabetes were diagnosed. In the low-risk group, 86 heart attacks, strokes or deaths were prevented, with no new cases of diabetes.

“We believe that most physicians and patients would regard heart attack, stroke and death to be more severe outcomes than the onset of diabetes, and so we hope that these results ease concern about the risks associated with statin therapy when these drugs are appropriately prescribed — in conjunction with improved diet, exercise and smoking cessation — to reduce patients’ risk of cardiovascular disease,” said Ridker in a statement.

Both the JUPITER trial and the new study were funded by AstraZeneca, maker of Crestor, and Ridker holds a patent for the test used to measure CRP in the trial.

The new study is unlikely to fully resolve the ongoing debate over administering statins to a healthy population. Many doctors think statins are already overprescribed as it is. As USA Todayreported:

Prescribing statins to people who don’t have heart disease “is still a big issue, despite what this paper says,” according to physician Eric Topol, director of the Scripps Translational Science Institute in San Diego. “Per 100 people you have two heart attacks less and one increase in diabetes. They’re trying to say it benefits more than it harms. But the benefit is so small.”

Topol says the patients he sees aren’t aware of the risks associated with taking statins. “The patient doesn’t know this might make their protection for heart attack marginally better but it also could backfire by inducing diabetes,” he says.

Still, if the current findings are confirmed in future studies, Gerald Watts of the University of Western Australia argues in an editorial accompanying Ridker’s study, the FDA may want to limit its diabetes warning on statins only to people with major risk factors for the disease. The main take-home message for both doctors and patients, he noted further, is that any patient at high risk for diabetes taking statins should be fully informed of the risks and carefully monitored.

But while heart disease is a major concern for people diabetes, that doesn’t mean all diabetes patients should be on statins. Physicians agree that the best prevention for Type 2 diabetes is exercise and a healthy diet.